But for a small period of time, Microsoft managed to steal some of Apple's thunder when news leaked that it was working on its own tablet, "The Courier."

Despite the excitement around the Courier, it never happened and we now know why.

Greene reports Microsoft's Windows chief Steven Sinofsky didn't want a tablet that didn't run on Windows. He wanted Microsoft to have one operating system to rule them all.

CEO Steve Ballmer was split. He asked Bill Gates for advice. Gates heard a presentation on the Courier, but when he learned it didn't have an email app he basically killed the project on the spot.

Microsoft's strategy of leaning on Windows served it well through the years, but in this case it's going to cause the company to be three years late to the tablet market. The Courier would have been ready in 2010.